DATES OF ELEVATION. 199 



contrary, may still be in progress. Not only so, but the 

 same evidence likewise tells that the Alps, Pyrenees, 

 Carpathians, the Caucasus, and the Egyptian Mokattam 

 range, as well as the mountains of Algeria, have all 

 attained their present elevation since the latter part of the 

 Eocene period, when at least a considerable portion of 

 their area was submerged. And we accordingly learn that 

 many of the most striking physical features of the Old 

 World are of comparatively modern origin. 



When, however, we turn to mountains like those of the 

 Lake District and Wales, which only attain moderate 

 elevations, and in which the rocks belong solely to the 

 Palaeozoic, or oldest geological epoch, it is evident that we 

 have to do with elevations of an extremely remote date. 

 There is, indeed, satisfactory proof that these old moun- 

 tains were once vastly higher than they are at present ; 

 their diminished altitude being due to the long ages during 

 which they have been subjected to the wear and tear of 

 the elements. To such mountains the proverb to which 

 we have already alluded is, therefore, strictly applicable ; 

 but in a geological sense the phrase " everlasting hills " 

 can be applied neither to the oldest nor the youngest 

 mountains. 



